Bicycle rear derailleur

ABSTRACT

A derailleur includes a base member for attachment to a bicycle frame and a movable member supporting a chain guide such that the chain guide moves laterally to shift a chain among a plurality of gears. The base member has a laterally inner surface and a laterally outer surface, and it includes a projection extending laterally outwardly for engaging a corresponding recess in the frame.

BACKGROUND OF THE INVENTION

[0001] The present invention is directed to bicycles and, more particularly, to a bicycle rear derailleur.

[0002] Bicycles typically include a frame, front and rear wheels, pedals that are used to rotate one or more front sprockets, a plurality of rear sprockets mounted to the rear wheel, and a chain that engages one of the plurality of front sprockets and one of the plurality of rear sprockets. A front derailleur mounted to the frame in close proximity to the plurality of front sprockets is used to shift the chain among the plurality of front sprockets, and a rear derailleur mounted to the frame in close proximity to the plurality of rear sprockets is used to shift the chain among the plurality of rear sprockets. The rider typically uses manual, electric, or hydraulic control devices to control the front and rear derailleurs.

[0003] Small bicycles that have a frame capable of folding upon itself to facilitate carrying on public transportation or storage at work facilities are becoming more popular. Because such bicycles are carried and stored in crowded places, they should be very compact. Thus, the sizes of the frame and wheels are minimized accordingly. Very often the frame folds in half in the middle so that the front wheel is placed adjacent to the rear wheel. Thus, the rear derailleur should be as compact as possible so as not to protrude excessively laterally and impact the front wheel, thereby preventing compact folding of the frame. Furthermore, the rear derailleur should not be so large or mounted so low on the frame as to strike the ground as the bicycle is being ridden.

SUMMARY OF THE INVENTION

[0004] The present invention is directed to a derailleur that is adapted to fit compactly on a bicycle frame. In one embodiment of the present invention, a derailleur includes a base member for attachment to a bicycle frame and a movable member supporting a chain guide such that the chain guide moves laterally to shift a chain among a plurality of gears. The base member has a laterally inner surface and a laterally outer surface, and it includes a projection extending laterally outwardly for engaging a corresponding recess in the frame. With this arrangement, the base member can be mounted to a laterally inner surface of the frame such that the projection engages a corresponding recess in the frame. The laterally inner mounting of the base member helps to minimize the lateral extent of the derailleur so as not to interfere with the folding of the frame, and the projection helps to securely position the derailleur on the frame without requiring additional positioning structures that would increase the overall size of the derailleur.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]FIG. 1 is a side view of a folding bicycle that includes a particular embodiment of a rear derailleur according to the present invention;

[0006]FIG. 2 is a more detailed view of the derailleur shown in FIG. 1;

[0007]FIG. 3 is a view taken along line III-III in FIG. 2;

[0008]FIG. 4 is a view illustrating the installation of the derailleur base member on the frame;

[0009]FIG. 5 is a detailed view of another embodiment of a rear derailleur according to the present invention; and

[0010]FIG. 6 is a view illustrating the installation of the derailleur base member on the frame.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011]FIG. 1 is a side view of a folding bicycle 10 that includes a frame 14 with a known folding joint 18 in the middle, a seat 12, a front wheel 22 mounted to a fork 26 that is rotatably mounted in a head tube 30 of frame 14, a handlebar assembly 34 for rotating the fork 26 and front wheel 22, a rear wheel 38 mounted to the rear of frame 14, a pedal assembly 42 rotatably mounted to frame 14 for rotating a front sprocket 46, a plurality of rear sprockets 50 mounted to the rear wheel 38, and a chain 54 that engages the front sprocket 46 and one of the plurality of rear sprockets 50. A rear derailleur 58 is mounted to the frame 14 in close proximity to the plurality of rear sprockets 50 for shifting the chain 54 among the plurality of rear sprockets 50. In this embodiment, a conventional manually operated shift control device 62 mounted to the handlebar assembly 34 controls rear derailleur 58 in a well-known manner. In other embodiments, multiple front sprockets 46 may be provided, and a front derailleur may be used to shift chain 54 among such a plurality of sprockets.

[0012]FIG. 2 is a more detailed view of derailleur 58 mounted to frame 14. Derailleur 58 includes a one-piece base member 70, a movable member 74 supporting a chain guide 78, and a link 82 directly connected between opposed coupling ears 84 on base member 70 and between opposed coupling ears 85 on movable member 74 through pivot pins 86 and 90, respectively. Movable member 74, and thereby chain guide 78, move laterally to shift chain 54 among the plurality of sprockets 50 in response to the operation of shift control device 62 in a well known manner.

[0013]FIG. 3 is a view taken along line III-III in FIG. 2, and FIG. 4 is a view illustrating the installation of base member 70 on frame 14. In this embodiment, frame 14 includes a recess such as a slot 94 that is contiguous with an axle opening 96, wherein axle opening 96 receives an axle 98 of rear wheel 38 therein. Axle 98 is a conventional quick-release axle comprising a hollow axle portion 102, a draw bar 106 having a threaded end portion 110, a threaded nut 114 screwed onto the threaded end portion 110, and a spring 118 disposed between nut 114 and frame 14. Element 122 is a hub locking nut that retains hollow axle portion 102 and other internal components to rear wheel 38.

[0014] Base member 70 has a laterally inner surface 130 and a laterally outer surface 134. Laterally outer surface 134 includes an outermost surface portion 136, a substantially flat and straight recessed surface portion 138, and substantially flat and straight stepped surface portions 142 and 146 extending between outermost surface portion 136 and recessed surface portion 138, wherein stepped surface portions 142 and 146 are substantially perpendicular to both outermost surface portion 136 and recessed surface portion 138. A projection 150 extends laterally outwardly from recessed surface portion 138 for engaging slot 94 in frame 14 as shown in FIG. 4. In this embodiment, projection 150 includes an outer projection surface 154 that is level with outermost surface portion 136, a substantially straight and flat first side wall 158, a substantially straight and flat second side wall 162, and a substantially straight and flat third side wall 166 extending between the end edges of first side wall 158 and second side wall 162. First side wall 158 is substantially parallel to second side wall 162, and third side wall 166 is substantially perpendicular to both first side wall 158 and second side wall 162. First side wall 158, second side wall 162 and third side wall 166 also are substantially perpendicular to recessed surface portion 138. Additionally, first side wall 158 and second side wall 162 are substantially perpendicular to stepped surface portions 142 and 146. Of course, none of the foregoing surfaces need to be straight, flat, perpendicular, parallel, recessed or flush, and the particular configurations may depend upon the application.

[0015] In this embodiment, a width WP of projection 150 between first side wall 158 and second side wall 162 is substantially equal to a width WS of slot 94. This allows base member 70, and hence derailleur 58, to be properly and snugly positioned on frame 14 without requiring additional positioning structures. Also, a width WA of axle opening 96 is substantially equal to width WS of slot 94. This allows hollow axle portion 102 to be inserted through the end of slot 94 to facilitate installation of wheel 38 to frame 14 without excessive play. Of course, these dimensions are not necessary and may be changed to suit the application.

[0016] Base member 70 includes a fastener opening 170 for receiving a fastener therethrough. Hollow axle portion 102 and draw bar 106 function as a fastener in this embodiment. Fastener opening 170 is disposed in close proximity to projection 150. Thus, the fastening and positioning of base member 70 to frame 14 can be accomplished very compactly without requiring dedicated fastening and positioning hardware.

[0017]FIGS. 5 and 6 are detailed views of a rear derailleur 200 which represents another embodiment of a derailleur according to the present invention. Derailleur 200 is constructed substantially the same as derailleur 58 in the first embodiment, so only the differences will be described in detail. In this embodiment, derailleur 200 includes a base member 204 that mounts to an extension 208 of frame 14 that extends downwardly from an axle opening 212. Extension 208 includes a fastener opening 216 and a recess 224 forming an abutment 228. Fastener opening 216 is adapted to receive a fastener 220 therethrough. Base member 204 includes a laterally inner surface (not shown), a laterally outer surface 232, and a fastener opening 234 for receiving fastener 220 therethrough. A projection 236 extends laterally outwardly from laterally outer surface 232, wherein projection 236 includes an arcuate first side wall 240, and arcuate second side wall 244, a third side wall 248 extending between one edge of first side wall 240 and second side wall 244, and a fourth side wall 252 extending between an opposite edge of first side wall 240 and second side wall 244. Fourth side wall 252 ordinarily abuts against abutment 228 formed by recess 224 when base member 204 is mounted to extension 208. As with the first embodiment, base member 204 is mounted to the laterally inner surface of extension 208.

[0018] In this embodiment, fastener 220 comprises a nut and bolt assembly. However, if desired, fastener opening 234 in base member 204 and/or fastener opening 216 in extension 208 may have a threaded inner peripheral surface, and fastener 220 may be a bolt that screws into one or both openings, with the bolt head being located either at the inner lateral surface of base member 204 or at the outer lateral surface of extension 208.

[0019] While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. For example, the size, shape, location or orientation of the various components may be changed as desired. The recess that receives the projection in the base member may be a simple depression or some other receding structure associated with the surface of the frame instead of the cutouts shown, or it may be a combination of such structures. Components that are shown directly connected or contacting each other may have intermediate structures disposed between them. The functions of one element may be performed by two, and vice versa. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the scope of the invention should not be limited by the specific structures disclosed or the apparent initial focus on a particular structure or feature. 

What is claimed is:
 1. A derailleur comprising: a base member for attachment to a bicycle frame, wherein the base member has a laterally inner surface and a laterally outer surface, wherein the base member includes a projection extending laterally outwardly for engaging a corresponding recess in the frame; and a movable member supporting a chain guide such that the chain guide moves laterally to shift a chain among a plurality of gears.
 2. The derailleur according to claim 1 wherein the base member includes an opening for receiving a fastener therethrough to attach the base member to the bicycle frame, wherein the projection is disposed in close proximity to the opening.
 3. The derailleur according to claim 1 wherein the base member is one-piece.
 4. The derailleur according to claim 1 wherein the movable member is coupled to the base member through at least one directly connected link.
 5. The derailleur according to claim 1 wherein the projection comprises: a first side wall; and a second side wall oriented substantially parallel to the first side wall.
 6. The derailleur according to claim 5 wherein the first side wall is substantially straight, and wherein the second side wall is substantially straight.
 7. The derailleur according to claim 5 wherein the projection further comprises a third side wall extending between the first side wall and the second side wall.
 8. The derailleur according to claim 7 wherein the first side wall is substantially straight, wherein the second side wall is substantially straight, and wherein the third side wall is substantially straight.
 9. The derailleur according to claim 8 wherein the third side wall is substantially perpendicular to the first side wall and to the second side wall.
 10. A derailleur apparatus comprising: a frame member having an axle opening for receiving an axle therethrough and a slot in close proximity to the axle opening; a base member attached to a laterally inner surface of the frame member, wherein the base member has a laterally inner surface and a laterally outer surface, wherein the base member includes a projection extending laterally outwardly into the slot in the frame member; and a movable member supporting a chain guide such that the chain guide moves laterally to shift a chain among a plurality of gears.
 11. The derailleur according to claim 10 wherein the projection has a width substantially equal to a width of the slot.
 12. The derailleur according to claim 10 wherein the slot has a width substantially equal to a width of the axle opening.
 13. The derailleur according to claim 10 further comprising a fastener extending through an opening in the base member for attaching the base member to the bicycle frame, wherein the projection is disposed in close proximity to the opening.
 14. The derailleur according to claim 10 wherein the base member is one-piece.
 15. The derailleur according to claim 10 wherein the movable member is coupled to the base member through at least one directly connected link.
 16. The derailleur according to claim 10 wherein the projection comprises: a first side wall; and a second side wall oriented substantially parallel to the first side wall.
 17. The derailleur according to claim 16 wherein the first side wall is substantially straight, and wherein the second side wall is substantially straight.
 18. The derailleur according to claim 16 wherein the projection further comprises a third side wall extending between the first side wall and the second side wall.
 19. The derailleur according to claim 18 wherein the first side wall is substantially straight, wherein the second side wall is substantially straight, and wherein the third side wall is substantially straight.
 20. The derailleur according to claim 19 wherein the third side wall is substantially perpendicular to the first side wall and to the second side wall.
 21. The derailleur according to claim 16 wherein a width of the projection between the first wall and the second wall is substantially equal to a width of the slot.
 22. The derailleur according to claim 21 wherein the width of the slot is substantially equal to a width of the axle opening. 